(CNN)-- Eight American soldiers died of overdoses involving heroin, morphine or other opiates during deployments in Afghanistan in 2010 and 2011, according to U.S. Army investigative reports.

The overdoses were revealed in documents detailing how the Army investigated a total of 56 soldiers, including the eight who fell victim to overdoses, on suspicion of possessing, using or distributing heroin and other opiates.

At the same time, heroin use apparently is on the rise in the Army overall, as military statistics show that the number of soldiers testing positive for heroin has grown from 10 instances in fiscal year 2002 to 116 in fiscal year 2010.

Army officials didn't respond to repeated requests for comment on Saturday. But records from the service's Criminal Investigation Command, obtained by the conservative legal group Judicial Watch, provided glimpses into how soldiers bought drugs from Afghan juveniles, an Afghan interpreter and in one case, an employee of a Defense Department contractor, who was eventually fired.

The drug use is occurring in a country that is estimated to supply more than 90% of the world's opium, and the Taliban insurgency is believed to be stockpiling the drug to finance their activities, according to a 2009 U.N. study. While the records show some soldiers using heroin, much of the opiate abuse by U.S. soldiers in Afghanistan involves prescription drugs such Percocet, the Army documents show.

Judicial Watch obtained the documents under the Freedom of Information of Act and provided them to CNN. Spokesman Col. Gary Kolb of the International Security Assistance Force, the NATO-led command in Afghanistan, verified the documents to CNN on Saturday.

One fatal overdose occurred in June 2010 at Forward Operating Base Blessing, after a soldier asked another soldier to buy black tar opium from a local Afghan outside the base's entry control point. The first soldier died after consuming the opium like chewing tobacco and smoking pieces of it in a cigarette, the documents show.

The reports even show soldier lingo for the drug -- calling it "Afghani dip" in one case where three soldiers were accused of using the opiate, the Army investigative reports show.

The United States has 89,000 troops in Afghanistan. The U.S. death toll since the September 11, 2001, attacks that triggered the war has risen to more than 1,850, including 82 this year, according to the U.S. Department of Defense and U.S. Central Command.

Tom Fitton, president of Judicial Watch, said his group was interested in soldiers' drug use partly because the risk was present during the Vietnam War.

"You never want to see news of soldiers dying of drug use in Afghanistan," Fitton said. "Our concern is, will the military treat this as the problem that it is, and are the families of the soldiers aware of the added risk in this drug-infested country?

"There is a dotted line between the uses. Prescription abuse can easily veer into heroin drug use," Fitton added. "Afghanistan is the capital of this opiate production and the temptation is great there and the opportunity for drug use all the more."

The group is concerned that "there hasn't been enough public discussion, and we would encourage the leadership to discuss or talk about this issue more openly," Fitton said.

In one case, a soldier bought heroin and the anti-anxiety drug Xanax from five "local national juveniles at multiple locations on Camp Phoenix, Afghanistan, and consumed them," one report states. Soldiers also distributed heroin, Percocet and other drugs among themselves, according to the reports.

Another soldier fatally overdosed in December 2010 after taking several drugs, including morphine and codeine, though the drugs were not prescribed for him, the Army documents show.

The investigative reports show soldiers using other drugs, including steroids and marijuana, and even hashish that was sold to U.S. servicemen by the Afghan National Army and Afghan National Police personnel, the reports state.

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